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Thursday, December 10, 2009

how to calculate quilt measurements

Math is a huge part of quilting, like it or not. I'm not particularly fond of math, but it's a necessity, especially since I rarely use a pattern.

I get emails all the time asking questions like:

"I'd like to make a twin size quilt out of charm packs. How many squares do I need?"

Or, "How many more blocks will I need to make the 9 patch quilt into a full size?"

Or, "I'd like to make your stacked coins quilt, but in a queen size. How many more charm packs and how much yardage would I need?"

These are just a few that come to mind. Well, today I'm going to walk you through these and show YOU how to do the math. :) Some of this may be pretty basic, but I think it's worth covering. I work with a calculator and a piece of paper and a pencil. No EQ for me. I'm old fashioned that way.

If you are making a quilt for a specific bed in your house, it's best to measure the top of your mattress and add the amount of overhang you want on each side, then you will have the perfect measurements for your bed. I'd recommend this, especially if you have a very deep mattress, or if you have head and foot boards to deal with. Or bunk beds.

These are target sizes. If your block calculations don't work out quite right, just round up.

Ok, for the the first question, how many charms will I need to make a twin size quilt?

The finished quilt measures 66" x 90" for the twin size. Each 9 patch block finishes at 6" and each sashing strip finishes at 2".

Since you want the quilt to be at least 78" wide, you will need 12 extra inches. You would need 20 extra blocks (ten for each additional column) and then add in the sashing 2" finished x 2 strips. The width of the twin quilt is 66" +12" (for the two extra columns of 9 patches) + 4" (for the two extra strips of sashing) =82", which is a bit wider than your target of 78", but close enough. Plus, it's nice to have it a bit too large than a bit too small. So the number of 9 patches needed would be 70 (from the original pattern) +20 = 90 for a full size quilt. Does that make sense?

Now, for the toughest one...a queen sized stacked coins quilt using this tutorial.

This one will be worked backwards. You want it to be 92" long. Subtract 6", for the top and bottom sashing, which will give you 86".

86" divided by 2" (finished height of each coin) =43.

So 43 coins in each column x 11 columns= 473 coins.

473 divided by 2 (number of coins that are cut from a charm pack)=236.5, which would be rounded up to 237 charm squares required.

If there are 40 charms in a pack, you would need 6 packs of charms.

For the yardage needed for sashing, you will need 12 strips that are cut 3.5" x 86" and 2 strips that are cut 3.5" x 85.5". For this step, I'd enter those numbers into the handy dandy quilt calculator (someone had directed to me awhile back, thanks to whomever did so, it's so very wonderful!) which will tell me that:for the 12 strips that measure 3.5" x 86"= 2.5 yards

for the 2 strips that measure 3.5" x 85.5"=2.375 yards

for a total of 4.88 yards, to which I would just round up to 5 yards.

Ok, any questions on how to do this? Remember to calculate with your FINISHED block size, not your CUT size, or you will have a quilt that will be much smaller than anticipated.

After all this, I feel compelled to ask, (like blogger does at the bottom of their help pages) was this article helpful to you? ;)

120 comments:

YES! I am new to quilting and I don't like to ask a lot of questions to quilters. I know quilters are helpful people but I get embarrassed OR I would bombard them with too many question. So, I love getting information on blogs as detailed as this. Thank you!!!

Thanks so much. I am fairly new to quilting and joined a group that had been together for a long time. Everytime I ask a question I get told "you should know that; we've talked about it". Only problem is that it was discussed long before I joined. This was so helpful.

This helps more than you know. I don't like math, but keep telling my kids learn it well you will need all your life. Think I will print your notes and keep in my reference binder. thanks for taking the time to write it all out for us.

Thanks AJ...I am going to FAV this post. Since I really just started quilting in June I have only used fabric I already had or remnants from the store. I have never bought a charm pack or jelly roll, etc., I just actually learned what everyone ment by those terms!:) So now I'll be able to purchase some of those items with a bit of knowledge!:)

I just found your blog a few days ago. It is awesome! Thanks so much for all the great and inspiring info! In answer to your question, this particular post wasn't a huge help to me just b/c I like doing the math :) but I am going to write down the target bed sizes - that's great info to have!

I have been spending lots of time going through your tutorials and other posts - what a wealth of great information! Such fun! Thanks so much for putting this together!

Great post! Thank you! I just have one question: At the end, for the coin quilt, you are essentially purchasing an extra 2.5 yards of sashing fabric in order to cut two 3.5" strips from it, right? So if you were willing to piece the sashing strips at top and bottom, you would be able to do this with much less "waste" (Not that buying fabric is ever a waste, but my wallet would appreciate it.)

WOW!!! How generous of you!! I used to work in a quilt shop and we got those questions all the time! It felt good to pull out some scrap paper, pencil and calculator and show the customer how to figure out the yardage, strips, length,etc for themselves!Libby

Wow! You are so great for putting together this post. Math is the part of quilting that people never talk about and it's key. As much as you try and avoid it, there's SOME math that always has to happen! Wonderful post.

I use EQ most of the time but also use a calculator when needed. Quilt math is easier than regular math :)

The question I get all the time is about fabric yardages although I state very clearly that I don't provide them with my instructions sheets since most of my quilts are made from scraps so I don't bother to calculate yardage even for myself.

Fantastic! I was calculating what size I needed to cut some squares recently to make some pinwheel blocks and my husband looked at my calculations and asked what I was doing. I said "quilt math" to which he replied (and I can say this here because most of us are women) "Is that like period math?" Sorry ladies, he's taken.

This will be so helpful in the future! I am just finishing up my first quilt ever from a pattern (so I knew how much to buy). Going forward I'd like to try some different stuff on my own and this will definitely come in handy.

Yes, thank you! I have a couple of quilts that I want to make, but don't have a pattern or have one for scraps but not amount of yardage needed. Your post today has inspired me to sit down with paper, pencil and calculator and . . . "just do it!"

Was this article helpful? YES! Extremely! It would have taken me about four eight hour days to figure all that out and get it written up in the very understandable form that you did. Thanks for going to the trouble.

Thank you sooooo much, this is extremely helpful. I wish I had some ink in my printer so I could print it out for easy reference. I was good at math at school, but have made so many sewing mistakes due to inaccurate math. Thanks for taking the time to explain all this, you are a very generous soul.Merry Christmas to you and yours.Kelly :-)

Oh man, I would never want to do a full size stacked coins quilt! I did a table runner, and did each strip the same, and yet when I added my sashing, the strips slowly got longer from one end to the other, so my rectangular table runner was almost triangular. Hated it, didn't want to rip it all out so I squared it up, cut off and wasted a bunch, and finished it. I can still tell it's wonky, and it makes me so mad!! I don't know where I went awry, if it was piecing the strips or adding the sashing, but I sure hated it, and will never to another one!!!

Amandajean thanks for taking the time to post this info. I always get nervous when calculating the measurements for a quilt. I check and double check and triple check before cutting the fabrics incase I stuff. This info has been very very helpful. I'm going to print it and pin it to my wall for future reference. Looking forward to seeing your next quilt. Carol

Funny you should post this today. I'm always asking my dh to help me with the math for how much yardage I need to buy in order to have the right amount for say borders. The basic formula is finding the area or base x height then dividing that by 1296 which is how many square inches in a yard. That'll give me one border so then I multiply it by two. Then do it again for the other two border pieces. Add it all up for the yardage.

My 2 cents is: I do mine visually. I create a photoshop document substituting cm for inches (ie for a cot size I'd do a 50x60 cm document for a 50"x60" quilt design) then I turn on 1cm grid lines... then I go to town until I'm happy... then I work out how much of each fabric from there. A little less maths and helpful while I'm sewing. ;)

Thanks for all the great info and for the link to the quilt calculator. That looks so neat. I use a pencil, calculator and graph paper. I make a rough drawing and then measure, and measure and remeasure.LOL!

This was great, Amanda Jean. It's what I do, but I've been asked a lot of questions about the math portion of quilting, and now I will just refer them to you. = ) You are awesome. I can't remember who said you were the Google of quilting blogs, but I would have to agree.

I too am not horribly fond of math, and to be honest EQ can be misleading so often I get out the paper and pencil, and use the calaculator on my computer or blackberry. That is very helpful for a lot of poeple thanks.

Wow! So informative! Thanks for sharing! I always seem to fuddle through my quilts, measuring twice, cutting once. And I always buy too much fabric (just to be on the safe-side). I love quilt math, but then again, I love any math, especially geometry! With your tips and pointers, perhaps I will now buy exactly what I need, rather than my guesstimation technique! LOL Thanks again!

well, you did it again. You took us to place no one dares to go: Math class. And look at all the happy people! Who would have guessed? ME: I "wing it" almost everytime I make a quilt and hardly ever know what size I'm going to end up with. You're such a good role model. :)

Don't normally leave a comment on your spot here as you always have SEVERAL, but I greatly enjoy seeing what you are doing quilt wise. If you get the chance to stop by my blog/journal, you will see I am a momma to two young blessings and enjoy learning new things in the home, I have a good relationship with my sewing machine. My math is HORRIFIC! So I read this entry carefully even trying to do the math for a quilt top I have in the making. It's one for our son and has my second time around with embroidery. So I got out my paper and did the math. I hope I did it right, now to double check it with my engineering husband. Poor guy is married to a creative person. *wink* He is my "calculator". *smile* I am working on my math and getting our children involved in math in the kitchen with recipies even though they are 4 & 2. *smile* It's never too earily to get to using your math. *big smile* Thank you for this entry and for breaking things down step by step. Sincerely, Mommy of two little blessings

You are toooooooo kind to leave tell everyone this. I guess since I learned from you I just learned to watch you and then figure them out myself! I guess it beats answering a million questions. Tooooooo kind I tell you! :)

Like you, I know the math is necessary but find this is the part that least thrills me. I just always want to get on with the sewing! (but I do know how important it is to get the math right first! ;o)

Wow, this is why your quilts always look so good- you actually plan them! I tend to make mine up as I go along, which leads to much angst over not having enough of particular fabrics once I get rolling. I never work to a particular end size- I just add borders until I get sick of wrestling them under the machine. I do admire your stacked coin quilts- I may just use your mathematical genius to make one! Love your blog. Susan

So what you're saying is, is that when I get questions asked of me... I just refer them to this post? I love the math part... just not explaining it. Echo'd voices of teachers past haunt me... "show your work, show your work".

As I only began quilting over a year ago, I really appreciate when more experienced quilters share helpful info. like you have done. I enjoy photos of quilts, but when I learn something about quilting, it is even better.

THANK YOU! for this post. I have been wanting to make quilts for my kids but had no idea how to measure and as much as I've looked I had yet to find anyone explain it as well as you do! Now they may get those quilts that they keep asking about. Now here's a teaser for you..about how many charm squares can you get out of a yard of fabric? :)

Thank you for this! I've just finished pieceing coin quilts for my two youngest girls using the info here and your tutorial on the Moda bakeshop, these are my first attempts at bed size quilts and you explaining the maths made it so much easier :) On to the quiting!

Seriously awesome (yes, I know I am posting a comment on a post from 2009...lol...but the "new" me has vowed to be more vocal in my appreciation...so, here you have it...LOL) I love this tutorial/lesson. Thank you!

Hi! I think I get it. I'm wanting to make a 36" X 36" table topper...if I apply your calculations to this I get a total of 64 charms. Also, my layout will be 8 blocks wide and 8 blocks long. Is this correct? It seems like a lot?? I'm awful with math, but I've just acquired the quilting bug! Please help if you can.Thanks,Angela

Thank you for this tutorial. I could have used this yesterday when trying to figure out how much fabric I needed for backing material. The lady at JoAnn's cutting table was very helpful. Will wait for my next 40% off coupon to by the backing.